The invention relates to a circuit breaker switching-off spring replacement device. The circuit breaker switching-off spring replacement device includes a supporting component, a rotating component and a spring tensioning component; and the spring tensioning component is movably connected with the supporting component through the rotating component, so that the spring tensioning component can rotate in a plane where the supporting component is located with the rotating component adopted as a fulcrum. When operation is performed, an installation hole at one end of a switching-off spring is fixed at a fixedly installed terminal of a circuit breaker, and a U-shaped clamping groove is inserted into the other end of the spring; and the supporting component is supported at the angle bar of the side angle of a circuit breaker mechanism; and the spring is tensioned to a direction opposite to a spring tensioning direction according to the lever principle, and one end head of the spring enters an installation hole, and thereafter is fastened by a nut; and the tool is removed, and the installation of the switching-off spring is completed. With the circuit breaker switching-off spring replacement device adopted, the switching-off spring of the circuit breaker can be replaced quickly, work efficiency can be improved, the safety of an operator can be ensured, and that is to say, high efficiency and safety can be both realized.